Gas flow control system



1955 N. s. STRANDWITZ ET AL 2,714,292

GAS FLOW CONTROL SYSTEM Filed Oct. 29, 1952 From lft hand From righthand bunk Pressure Gauge INVENTORS, NORMAN S. STRANDWITZ FRANCIS J.EIGHELMAN WILLIAM E. DOERING BY ATTORNEY United States Patent GAS FLOWCONTROL SYSTEM Norman S. Strandwitz, Chicago, Francis J. Eichelman,

Brookfield, and William E. Doering, Chicago, Ill., assignors to NationalCylinder Gas Company, Chicago, IlL, a corporation of DelawareApplication October 29, 1952, Serial No. 317,534

Claims. (Cl. 62-1) This invention relates in general to a gas flowcontrol In such installations, the consumers piping and distributingsystem is generally supplied with gas from a group or groups ofcylinders manifolded together and known as the service supply, with asecond or reserve supply of manifold cylinders connected and inreadiness to supply the system when the service supply becomes exhaustedand while it is being replenished. The former reserve supply thenbecomes the service supply and when the exhausted source has beenreplaced by fully charged cylinders, it then becomes the stand-by orreserve supply. In many gas consuming installations, this change overmay be accomplished manually by the reversal of a simple T valve or thelike between the service and reserve supplies and the line when theimminent exhaustion of the service source is observed. However, in aninstallation such as a hospital, where lives may be dependent on acontinuous and uniform flow of a gas, such as oxygen, a simple manualswitching system subject to human error cannot and should not be reliedon to the extent inherently necessary. Accordingly, particularly forhospital installations, it has been known to provide a pair ofinterconnected pressure reducing valves or regulators each associatedwith one of the banks of cylinders or other supply sources anddifferentially pre-set to automatically change over from the servicesupply to the reserve supply when the pressure in the service supply2,714,292 Patented Aug. 2, 1955 tive, the remaining regulator of thepair and a line regulator can be utilized to maintain a uniform flowfrom either of the alternate supply sources to the consumers systemwhile the inoperative regulator is repaired or replaced. Likewise, ifone of the pair of change over regulators and the line regulator bothbecome inoperative, the single remaining regulator can maintain auniform flow pressure.

Accordingly, it is the principal object of this invention to provide anautomatic change over flow control arrangement whereby a steady anduniform flow of gas to the consumers installation is maintainednothwithstanding that one or more of the regulators of the system may beout or order or become inoperative.

Another object of the invention is to provide a simple and foolproof gasflow control system which does not require the services of amechanically skilled attendant, and may be operated easily by anyone. Itwill be apparent that this feature is of great benefit in hospitalinstallations.

It is a further object to provide a uniform gas flow control arrangementwhich is tamperproof, and which has an inherent high degree of safetyand dependability in operation so'that under no circumstance will theuniform flow of gas be interrupted.

Another object of the invention is to provide asimple mechanical resetmechanism so that after an automatic change over of supply source, thedifferential settings of the linked regulators may be easily reversedwithout internal adjustment.

An outstanding feature of the invention resides in its compactarrangement whereby it canbe readily encased in a locked cabinet withonly a reset lever and three piping connections extending therefrom sothat the entire flow control arrangement can be made substantiallytamperproof.

Additional features and advantages will become apparent as the followingdescription proceeds particularly taken in conjunction with theaccompanying drawings wherein:

Fig. 1 is a diagrammatic showing of a preferred embodiment of uniformgas flow control system provided by this invention;

Fig. 2 is a plan view of a portion of the system of Fig. I particularlyshowing the manner in which the differentially set change overregulators of the system are fell to a near exhaustion pressure andlower by the differential amount than the presetting of theservice'regulator, and to then give an appropriate alarm announcing thatcondition. Although such an automatic change over is an improvement overreliance upon human observation and manual operation, the systemsheretofore provided had the serious disadvantage of being subject to apresfull supply source, such as a bank of manifoldedcylinders,

sure drop in the line from the desired line pressure when the servicesupply was approaching exhaustion and prior to the automatic change overto the reserve supply. After the change over occurred, it wasaccompanied by an I equally disadvantageous surge or increase in theline pressure up to the desired line pressure when the second regulatorof the pair was reset, as was obviously required in such cases.

The system of this invention overcomes all of the disadvantages inherentin previously known expedients and is capable of maintaining acompletely uniform line pressure notwithstanding a differential settingof the pair of automatic change over controlling regulators.Furthermore, it provides means where if either of the differentially setchange over regulators should become inoperalinked and the means wherebythe reversing of the differential settings may easily be accomplished inthe reset operation; and

Fig. 3 is a sectional view on line3-3 ofFig. 2.

Assuming that a right hand bank of manifolded gas cylinders or otherhigh pressure supply source not shown) is considered the service supplyfor the purposes of illustration, the invention is best described bytracing the flow of gas in Fig. 1.

Gas, such as oxygen, at relativelyhigh pressure from a under an initialpressure in the range of 2400 to .2600 p.'s. i., depending'upon the sizeand construction of the supply source, flows through right hand header10 and normally open valve 11. As by-pass valve 12 is normallymaintained closed unless a special condition arises which will bedescribed later, the gas from the right hand supply source, presentlyconsidered the service supply, flows through another valve 13, highpressure reducing valve or regulator 14 and check valve 15 into adelivery'header 16, which may also be a hollow mountingblock orbar. Thehigh pressure reducing regulator 14 is preset to deliver on its outletside, that is, through the check valve L15, to header 16, gas under areduced pressure, which for the purposes of illustration may beconsidered to be p. s. i. At the same time a left hand high pressuresupply source, such as a second bank of manifolded gas cylinders (notshown) connected to left hand header 17, may be considered for thepurposes of illustration as the reserve gas supply. Left hand valves 18and 19, like the corresponding right hand valves 11 and 13, are normallyopen so that if there were no restraining circumstance, gas would alsoflow from this supply through high pressure reducing valve or regulator20 and check valve 21 to the header 16. However the regulator 20 ispreset to deliver gas on its outlet side at a constant pressure somewhatbelow the delivery pressure for which the regulator 14 is preset, forexample, at 70 p. s. i. Thus, there exists a differential of 10 p. s. i.between the delivery pressure of the two regulators 14 and 20. Ingeneral, a pressure differential between these regulators should be atleast to 7 p. s. i., and a differential in the neighborhood of 10 to 12p. s. i. is preferred. Both regulators 14 and are conventional highpressure reducing regulators and may be either single or double stage,stem or nozzle types, or a combination of these, all of which types ofregulators are well known. Preferably, these high pressure reducingregulators are of the type disclosed in copending application Serial No.778,939, filed October 9, 1947, now Patent No. 2,651,147 issuedSeptember 8, 1953. Regardless of the specific type of regulatorsprovided, the pair of regulators 14 and 2G constitute the differentiallypreset automatic change over mechanism of the system.

In view of usual regulator construction, as well as the construction 'ofthe preferred type of regulators shown in copending application SerialNo. 778,939, the fact that regulator 20 is preset to deliver gas at apressure lower than that delivered by regulator 14, precludes the flowof gas from the left hand or reserve supply until the regulator 14 is nolonger able to maintain its constant delivery pressure due to the nearexhaustion of the right hand supply source with consequent reduction ofits pressure to a value below the present delivery pressure of regulator20. In theembodiment here illustrated, this would mean that no gas willflow from the reserve supply into header 16 until the pressure in theservice or right hand supply has diminished to 70 p. s. i., at whichtime the delivery of gas at 70 p. s. i. pressure from the reserve supplyto header 16 will immediately commence through regulator 20, as will bedescribed more fully subsequently. Meanwhile, gas from' the service orright hand supply is being delivered to the header 16 at a constantpressure of 80 p. s. i. and because of check valve 21 and the inherentnon-reversible flow construction of pressure reducing regulators ingeneral, as well as the full higher pressure in the reserve supply, noreverse flow of gas toward the reserve supply can occur. The gas fromthe service supply, therefore, flows from header 16 through valve 22,which is normally open, line regulator 23, check valve 24 to consumersline 45 as indicated in Fig. l. A secondary by-pass valve 25 is normallyclosed so that the gas follows the path just traced and does not flowthrough sec- ,ondary by-pass piping or conduit 26. The secondaryby-passing piping 26 is coupled into the flow path just describedup-stream of check valve 22 by means of a T connection 27 and into theconsumers line downstream of check valve 24 by means of a crossconnection 28, for the purpose of providing a by-pass flow of the gas inthe event that line regulator 23 is in need of repair or is beingreplaced.

There is further provided at the cross connection 28 down-stream ofcheck valve 24, a relief valve or safety release 29, which shouldpreferably be vented to the open atmosphere. This relief valve 29 may bepreset at any desired release pressure depending on the apparatus in theinstallation which it is designed to protect as well as on the finalline pressure setting for which regulator 23 is preset.

Regulator 23 may again be any type of conventional gas pressure reducingregulator but is preferably a line type regulator; that is' to say, itis designed merely to further regulate an already reduced, relativelylow delivery pressure from a high pressure regulator, such as either 14or 20. For purposes of illustration, it may be assumed that lineregulator 23, which may be either single or double stage, nozzle or stemtype, is in fact a stern type, single stage, line regulator designed foran approximate inlet pressure of not more than 300 p. s. i. and in theembodiment here being described is preset to deliver a constant outletor line pressure to the distributing system in the neighborhood of 50 to60 p. s. i. It will be seen, therefore, that regulator 23 in theillustrated example is not required to regulate or to reduce pressuresthrough a range greater than about 20 to 30 p. s. i., since as hasalready been described, regulator 14 is preset to deliver p. s. i. andthe outlet delivery pressure of line regulator 23 normally would not beless than 50 p. s. i., particularly in hospital installations. The flowof gas from the service supply thus traced will continue at a constantdelivery pressure until the service or right hand supply becomessubstantially exhausted, or when the gas pressure at the supply sourceis diminished to 78 p. s. i. or less. At this point regulator 20, whichthus far has been considered the reserve supply regulator, automaticallytakes over and begins delivering gas to the header 16 at its presetdelivery pressure of 70 p. s. i. Gas from this source then follows thesame flow path previously described through the T 27, valve 22, lineregulator 23, check valve 24 and cross connection 28 to the line 45. ItWill be noted that the all-important factor of continuous flow of gas atconstant pressure to the installation is thus maintained by theoperation of line regulator 23, notwithstanding any slight variation ingas pressure delivered to header 16. Therefore, in an installation, suchas a hospital, the essential requirement of a constant flow of oxygen isconstantly maintained at a uniform, steady line or flowing pressurewithout manual manipulation.

As the pressure from the right hand or service supply drops from 80 to70 p. s. i., the pressure in header 16 also diminishes until it alsoreaches the pressure (70 p. s. i.) at which the left hand or reservesupply is automatically put into service. A mercury contact pressuregauge 3%, preset to close an electrical circuit when the pressure inheader 16 falls to the predetermined pressure, here 70 p. s. i., thenoperates to close the circuit at its contacts schematically shown at 31,lighting an incandescent lamp 32 from any suitable power sourcegenerally indicated at 33. It will be understood that power source 33 isshown in the drawing as a battery only for purposes of illustration, andmay equally well be a power tap to the available electrical supply lineat the installation.

When lamp 32 is lit, it operates as a signal to indicate that theservice supply of gas has become exhausted, and that the installation isbeing served by the reserve supply. Other indicia (not shown) may alsobe provided which, when the lamp 32 is lit, simultaneously becomevisible or audible, or both, in various locations as desired. Suchindicia may preferably comprise lighted instructions to be then followedby service personnel. For example, it would be necessary to arrange forreplenishment of the right hand supply source of gas, and thereupon itis merely necessary to move reset lever 35 to its opposite or remoteposition. This latter action automatically and instantaneously resetschange over regulator to the higher differential pressure of 80 p. s. i.used in this example, andthe right hand change over regulator 14 is bythe same action reset to the lower delivery pressure of 70 p. s. i. Theleft hand source then becomes the service supply and, when replenished,recharged, or replaced, the right hand source becomes the reservesupply. As noted briefly before, the gas from the left hand supply (nowthe service supply) cannot flow back into or equalize with the exhaustedsupply source because of the check valve 15 and the inherentnonreversible flow construction of gas pressure reducing regulators.Moreover,

animus as isoontasthe reset .lever.35 has been rmoved thus resettingregulator 20 to the .higher delivery pressure and thereby increasing gaspressure :to the header 16, the

mercury contact pressure gauge 30operates to open the signallingcircuitso that the-lamp 32is extinguished, and other indicia returned .to.normal. The operation then continues usinggas .from the left handsupply until it becomes depleted to a pressure of 70 p. s..i., whereuponthe replenished right hand reserve supply automatically goes on streamin the manner .previously described, .and with nodelay and nolossoflinepressure to the installation. In this manner, .the'operationcontinues with the supply sources being alternated from service toreserve status as they are alternately .depletedand replenished withonly the reset lever .35 being moved from its one extremepositiontotheother-when the exhausted supply source is replenished.

The instantaneous readjustment and reversal of .thedifferential.pressuresettingofthe change over regulators 20 and .14 isaccomplished by.movement of reset lever .35 as isillustrated invFigs. 2and 3, and described in detail hereinafter. In the case of allconventional gas pressure regulators .the delivery pressure .from the.re gulater is diminished by rotating their adjusting screwscounterclockwise, and reverse rotation serves to increase the deliverypressure. The regulators 14 and 20 are arranged with their adjustingscrews .36 toward each other as shown in the enlarged .view of thatportion of the system shown in Fig. .2, and the .free ends of theseadjusting screws 36 of both regulators 214 and..20,.instead ofterminating in a conventional .hand wheel are each provided with a nut37, which in the embodiment illustrated .is hexagonal. A reset leversleeve 38 .which is internally broached to a complementaryzhexagonalshape that fits closely over the'ends 37.0f theregulator screws 36 isprovided to link the free ends .37 of theregulator adjusting screws v36.Suitable securing means, such as set screws.39, are provided to hold thesleeve 38 .inplace. A suitable lever arm 40 of .the reset leverarrangement 35 is secured in any suitable manner, such as by silversoldering, atjoint 41 to thesleevelink .38, and the outer or free end ofthe lever arm 4.0 is provided with a.knob 42. When the reset lever 40 isrotated, obviously one regulator adjusting screw 36 will be rotatedclockwise and the other counterclockwise. .Theregulators are adjusted sothat a single movement, of forexample, through .an arc of 90, of resetlever 35 will respectively raise and lower the preset delivery pressureby the desired diflerential value, thereby .reversing the preselecteddelivery pressures of regulators 14 and 20. Thus, with leverarm 40 initsdown .position (Fig. l), the regulator 14 as has been .describedintheexample .for illustration, delivered a pressure to-header .16 higher bythe desired differential value than that deliverable .bythe regulator 20due to the preselected initial adjustments of thetwo regulators. Afterthe right-hand supply source'has been replenished, lever 40 of the resetarrangement 35 is moved to its opposite or up position whereby adjustingscrew 36 of the regulator 14 isrotated counterclockwise diminishing itsdelivery pressure setting while adjusting screw 36 of the regulator 20is rotated clockwise thereby increasing its delivery pressure setting.The converse action occurs after the left hand source is.replenished. Itwill therefore be seen-that this simple .movement'of lever arm 46 fromone position to the other effectively reverses the delivery pressureadjustments of the regulators 14 and20.

The entire arrangement is sufficiently compact so that it may be easilyencased'in a cabinet provided with a slot in its facethrough which thereset lever arm '40 extends. The slot may be of such a length that .itis only possible to rotate thelever 40 through an arc of about 90. 'Thecabinet may also be .arranged so that only the conventional-pressuregauges (not shown) of regulators 14, 20, and 23 are visible from theoutside .of the cabinet and .withtresetleverarm 40 appear on theface ofthe cabinet. The pressure gauges of regulators 14 and 20 will alwaysindicate the pressures of their respectively associated supply sourcesand the gauge of regulator 23 will indicate the line pressure at whichthe gas is being supplied to the installation. .Furthermore, the onlymembers other than .reset .lever 40 which extend outside of the cabinetare suitable header connections for supply headers .10 and .17, and the.line 45 to the distributing system of the installation.

Within the cabinet, and not visible from the outside, there are provideda service pressure gauge 43 anda service valve 44 connected into header16. The service gauge 43 and service valve 44 are provided for theconvenience of service personnel in the event that one of the elements,such as a regulator, .fails to function properly. Furthermore, thevarious valves, such as valves 11, 12, 13, 18, '19, 22 and 25, Whosefunctions have .not previously been described, may be enclosed withinthe cabinet so that should one of the automatic change over regulators14 or 20, for instance, or line regulator 23, fail to function, orshould both line regulator 23 and one of thechange'over regulators 14 or20 become inoperative,

the unit may be temporarily adjusted to enable the remaining regulatoror regulators, as the case may be, to continue to supply theinstallation without interruption or pressure change while the necessaryrepair or replacement is made.

Assuming that the left hand supply is operating as the service sourceand regulator 20, preset to deliver p. s. i., begins to deliver anincreased pressure due to a defect, line regulator 23 will maintain auniform pressure .and flow of gas to theline45 despite higher pressuresat its inlet side. In this case service gauge 43 on inspection of thesystem will reveal the increased pressure delivered by regulator20 toheader 16, and valves 19 and 11 may then be closed while by-pass valve12 is opened, although not necessarily in the order named, whereby gasfromthe service supply is by-passed through valve 12 and the bypassconduit in which it is located, and through valve 13 to regulator 14.Valve 11 is closed to prevent gas from the reserve supply source, whichnormally will be at a higher pressure than the operating supply, fromequalizing with the partially depleted service supply when the bypassvalve 12 is opened. Regulator 20 may now be removed With no loss of gasfrom header 16 because of the check valve 21. The regulator 20 thus maybe in spected, repaired or replaced while regulator 14 serves the systemfrom the left hand source via header 16 and line regulator 23. If theleft hand supply becomes depleted while'this situation prevails, thebypass valve 12 may be closed and valve 11 opened whereupon regulator.14 will serve the system from the right hand supply. Alternatively,by-pass valve 12 may remain open if both valves 18 and 19 are closed. Itwill be observed there- 'fore, that in an emergency, either ofregulators 14 or 20 can operate individually from either source withoutinterruption .of serviceto the system.

Before theregulator .20 is returned to service, the delivery pressurefrom regulator 14 may be ascertained by momentarily bleeding gas fromthe header 16 through service .valve 44 and observing service gauge 43.If necessary or desirable, adjustment may then be effected by means ofadjusting screw 36 of regulator 14. Regulator 2%) may then be returnedto service by closing the bypass valve12 and opening valve 19. Thedelivery pressure of regulator2tl likewise can be determined after amomentary bleeding of the header 16 through service valve44, and ifnecessary, regulator .20 can be adjusted before the reset lever linkagesleeve 38 is secured in place.

Conversely, in the event that regulator 14 malfunctions, .gas from theright hand supply can be by-passed to the regulator 20 by acorresponding manipulation of the valves, that is, by closing valves 18and Band opening by-pass valve 12. The regulator 14 may then be removed,while check valve prevents loss of pressure in header 16.

Similarly, in the event that line regulator 23 becomes inoperative, orfails to function, valve 22 may be closed and secondary by-pass valve 25opened so that regulator 23 may be removed, repaired or replaced. Thesupply of gas to the line continues and the system remains closed bymeans of check valve 24. If the installation is such as to require thatthe line pressure be maintained at not more than p. s. i., it is onlynecessary that one of the regulators 14 or 20 be suitably adjusted priorto the opening of secondary bypass valve 25. The other of regulators 14and 20 is then precluded from operation by closing either valve 13 or 19as the case may be. The thus adjusted regulator of the change over pair,either 14 or 20, will then temporarily deliver gas at the desired linepressure until the line regulator 23 is returned to service.

In the event that both of regulators 23 and 20 or both of regulators 23and 14 become simultaneously inoperative, the remaining regulator,either 14 or 20, may be employed to maintain uniform, uninterrupteddelivery of gas to the system by appropriate manipulation of the valvesystem described. It will therefore be apparent that short of a'complete breakdown, which is exceedingly unlikely by reason of thearrangement described, a continuous, uniform and uninterrupted flow ofgas may be maintained to the distributing system at all times, and witha high degree of flexibility in operation.

It will be understood that this invention resides in the novelcombination, arrangement and adaptation of parts and that suchmodifications as will suggest themselves to those skilled in the art andwhich come within the spirit of this invention are included within itsscope as defined by the appended claims.

We claim:

1. In a gas flow control system for maintaining a uniform flow of gas atpredetermined pressure from a plurality of alternate sources at varyinghigher pressures wherein a pair of high pressure reducing regulatorsadjusted to deliver gas at pressures differing by a preselecteddifierential value and each of which is connected to at least one ofsaid sources through a common header to 'a third relatively low pressurereducing regulator whereby decrease of pressure in the source connectedto the regulator of said pair adjusted to deliver the higher of saiddilferential pressures to or below the pressure for which the other ofsaid pair of regulators is adjusted, will auto matically cause gas to bedelivered through the latter regulator from one of the plurality of thealternate sources to which it is connected, the improvement comprisingpositioning said pair of regulators with their adjusting screws towardeach other, mechanical linking means comprising a sleeve connecting thepressure adjusting screws of said pair of regulators, means for rotatingsaid sleeve through an arc whereby the differential adjustment of saidpair of regulators may be reversed and reset, and a plurality of valvesfor said pair of regulators associated with conduit means operable sothat either regulator of said pair may be removed and the remainingregulator of the pair connected to any of said alternate sources withoutinterruption of gas flow, said plurality of valves comprising a valve onthe inlet side and a check valve on the outlet side of each of said pairof regulators and a by-pass valve between the inlets of said pair ofregulators upstream of said valves.

2. A gas flow control system for delivering gas at a substantiallyuniform predetermined pressure to a consumers line from either of a pairof separate gas sources of higher pressures, comprising a pair of highpressure regulators each having an inlet side and an outlet side, athird relatively low pressure regulator having an inlet side and anoutlet side adapted to be connected to said consumers line, meansconnecting the inlet side of said low pressure regulator to the outletsides of both of said high pressure regulators, conduits interconnectingthe inlet sides of both of said high pressure regulators with both ofsaid gas sources, and selectively operable valve means included in saidconduits and selectively controllable to deliver gas from either of saidsources to the inlet side of either of said high pressure regulators,whereby either of said high pressure regulators may be removed fromservice without interrupting the flow of gas to said consumers line.

3. A gas flow control system for delivering gas at a substantiallyuniform predetermined pressure to a consumers line from either of a pairof separate gas sources of higher pressures, comprising a pair of highpressure regulators each having an inlet side and an outlet side,conduits separately connecting the inlet sides of said regulators todifferent ones of said sources, a third relatively low pressureregulator having an inlet side and an outlet side adapted to beconnected to said consumers line, means connecting the inlet side ofsaid low pressure regulator to the outlet sides of both of said highpressure regulators, a by-pass conduit interconnecting said firstnamedconduits to deliver gas from either of said sources to the inlet side ofthe high pressure regulator to which the source is not separatelyconnected, and selectively operable valves included in said by-passconduit and said first-named conduits and selectively controllable toeffect the delivery of gas through said conduits from either of saidsources to the inlet side of either of said high pressure regulators andto cut ofi the delivery of gas to the inlet side of the other highpressure regulator, whereby either of said high pressure regulators maybe removed from service without interrupting the flow of gas to saidconsumers line.

4. A gas flow control system for delivering gas at a substantiallyuniform predetermined pressure to a consumers line from either of a pairof separate gas sources of higher pressures, comprising a pair of highpressure regulators each having an inlet side and an outlet side, athird relatively low pressure regulator having an inlet side and anoutlet side adapted to be connected to said consumers line, meansconnecting the inlet side of said low pressure regulator to the outletsides of both of said high pressure regulators, conduits interconnectingthe inlet sides of both of said high pressure regulators with both ofsaid gas sources, selectively operable valve means included in saidconduits and selectively controllable to deliver gas from either of saidsources to the inlet side of either of said high pressure regulators,whereby either of said high pressure regulators may be removed fromservice without interrupting the flow of gas to said consumers line, andmeans including a by-pass conduit connected across said low pressureregulator for delivering gas to said consumers line directly from theoutlet sides of either of said high pressure regulators withouttraversing said low pressure regulator, whereby said low pressureregulator may be removed from service without interrupting the flow ofgas to said consumers line.

5. A gas flow control system for delivering gas at a substantiallyuniform predetermined pressure to a consumers line from either of a pairof separate gas sources of higher pressures, comprising a pair ofadjustable high pressure regulators each having an inlet side and anoutlet side, a third relatively low pressure regulator having an inletside and an outlet side adapted to be connected to said consumers line,means including a header commonly connected to the outlet sides of saidhigh pressure regulators for delivering gas from said high pressureregulators to the inlet side of said low pressure regulator, means foradjusting the delivery pressures of said high pressure regulators sothat the outlet side gas pressure of one of said high pressureregulators is appreciably higher than the outlet side gas pressure ofthe other of said high pressure regulators, whereby gas is delivered tosaid common header through said other high pressure regulator only whenthe outlet side gas pressure of said one high pressure regulator dropsto a value not exceeding the outlet side gas pressure of said other highpressure regulator, conduits interconnecting the inlet sides of both ofsaid high pressure regulators with both of said gas sources, andselectively operable valve means included in said conduits selectivelycontrollable to deliver gas from either of said sources to the inletside of either of said high pressure regulators.

6. A gas flow control system for delivering gas at a substantiallyuniform predetermined pressure to a consumers line from either of a pairof separate gas sources of higher pressures, comprising a pair ofadjustable high pressure regulators each having an inlet side and anoutlet side, a third relatively low pressure regulator having an inletside and an outlet side adapted to be connected to said consumers line,means including a header commonly connected to the outlet sides of saidhigh pressure regulators for delivering gas from said high pressureregulators to the inlet side of said low pressure regulator, means foradjusting the delivery pressures of said high pressure regulators sothat the outlet side gas pressure of one of said high pressureregulators is appreciably higher than the outlet side gas pressure ofthe other of said high pressure regulators, whereby gas is delivered tosaid common header through said other high pressure regulator only whenthe outlet side gas pressure of said one high pressure regulator dropsto a value not exceeding the outlet side gas pressure of said other highpressure regulator, signaling means operated upon the occurrence of adrop in gas pressure in said common header to a pressure less than theoutlet side gas pressure of said one high pressure regulator, conduitsinterconnecting the inlet sides of both of said high pressure regulatorswith both of said gas sources, and selectively operable valve meansincluded in said conduits and selectively operable to deliver gas fromeither of said sources to the inlet side of either of said high pressureregulators.

7. A gas flow control system for delivering gas at a substantiallyuniform predetermined pressure to a consumers line from either of a pairof separate gas sources of higher pressures, comprising a pair ofadjustable high pressure regulators each having an inlet side and anoutlet side, a third relatively low pressure regulator having an inletside and an outlet side adapted to be connected to said consumers line,means including a header commonly connected to the outlet sides of saidhigh pressure regulators for delivering gas from said high pressureregulators to the inlet side of said low pressure regulator, means foradjusting the delivery pressures of said high pressure regulators sothat the outlet side gas pressure of one of said high pressureregulators is appreciably higher than the outlet side gas pressure ofthe other of said high pressure regulators, whereby gas is delivered tosaid common header through said other high pressure regulator only whenthe outlet side gas pressure of said one high pressure regulator dropsto a value not exceeding the outlet side gas pressure of said other highpressure regulator, means for changing the adjustment of said highpressure regulators to increase the outlet side gas pressure setting ofsaid other high pressure regulator to that of said one high pressureregulator and simultaneously to decrease the outlet side gas pressuresetting of said one high pressure regulator to the initial outlet sidegas pressure setting of said other high pressure regulator, conduitsinterconnecting the inlet sides of both of said high pressure regulatorswith both of said gas sources, and selectively operable valve meansincluded in said conduits and selectively operable to deliver gas fromeither of said sources to the inlet side of either of said high pressureregulators.

8. A gas flow control system for delivering gas at a substantiallyuniform predetermined pressure to a consumers line from either of a pairof gas sources of higher pressures, comprising a pair of high pressureregulators each having an inlet side and an outlet side, conduitsseparately connecting the inlet sides of said regulators to differentones of said sources, a third relatively low pressure regulator havingan inlet side and an outlet side adapted to be connected to saidconsumers line, means including a header commonly connected to theoutlet sides of said high pressure regulators for delivering gas fromsaid high pressure regulators to the inlet side of said low pressureregulator, means including a. bypass conduit connected across said lowpressure regulator for delivering gas to said consumers line directlyfrom said header without traversing said low pressure regulator, wherebysaid low pressure regulator may be removed from service withoutinterrupting the flow of gas to said consumers line, one of said highpressure regulators being operative to deliver gas to said common headerat an appreciably higher pressure than the other of said high pressureregulators, whereby gas is delivered to said common header through saidother high pressure regulator only when the outlet side gas pressure ofsaid one high pressure regulator drops to a value not exceeding theoutlet side gas pressure of said other high pressure regulator, andsignalling means operated upon the occurrence of a drop in gas pressurein said common header to a pressure less than the outlet side gaspressure of said one high pressure regulator.

9. A gas flow control system for delivering gas at a substantiallyuniform predetermined pressure to a consumers line from either of a pairof separate gas sources of higher pressures, comprising a pair of highpressure regulators each having an inlet side and an outlet side,conduits connecting the inlet sides of said high pressure regulators tosaid sources, a third relatively low pressure regulator having an inletside and an outlet side adapted to be connected to said consumers line,means including a header commonly connected to the outlet sides of saidhigh pressure regulators for delivering gas from said high pressureregulators to the inlet side of said low pressure regulator, said highpressure regulators being povided with outlet pressure adjusting screwsarranged in axial alignment, adjustable linking means interconnectingthe ends of said adjusting screws for uni-control operation thereof andnormally so set that the outlet side gas pressure of one of said highpressure regulators is appreciably higher than the outlet side gaspressure of the other of said high pressure regulators, whereby gas isdelivered to said common header through said other high pressureregulator only when the outlet side gas pressure of said one highpressure regulator drops to a value not exceeding the outlet side gaspressure of said other high pressure regulator, and a lever extendingoutwardly from said linking means and rotatable about the axis of saidadjusting screws to change the adjustment thereof so that in response tolimited movement of said lever the outlet side gas pressure setting ofsaid other high pressure regulator is increased to that of said one highpressure regulator and the outlet side gas pressure setting of said onehigh pressure regulator is decreased to the initial outlet side gaspressure setting of said other high pressure regulator.

10. A gas flow control system as claimed in claim 9, wherein saidlinking means comprises nutted ends for the outer extremities of saidadjusting screws and an elongated element provided with an internalopening at each end having a complementary shape to closely fit over andengage said nutted ends, said lever is connected to and projectsoutwardly from said elongated element, and screw means are provided forconnecting said elongated element to said nutted ends of said adjustingscrews.

References Cited in the file of this patent UNITED STATES PATENTS2,168,701 Buttner Aug. 8, 1939 2,352,627 Grant, Jr. July 5, 19442,517,049 Stevens Aug. 1, 1950 2,578,042 Chandler Dec. 11, 1951

